Two more actors have joined the cast of “Patriots Day,’’ one of two movies currently being made about the Boston Marathon bombings. Rachel Brosnahan, whose resume includes a role on “House of Cards,’’ and Christopher O’Shea, who’s appeared on the CBS show “Madame Secretary,’’ will play Jessica Kensky and Patrick Downes, newlyweds who were near the finish line when the bombs exploded and both lost limbs as a result of their injuries. “The survivors are the heart of this story and Rachel and Christopher are bringing their immense talents and their respect for Jessica and Patrick’s extraordinary courage to the film,’’ the film’s director, Peter Berg, said in a statement. Brosnahan and O’Shea join a cast that includes Mark Wahlberg, John Goodman, J.K. Simmons, Michelle Monaghan, Kevin Bacon, Michael Beach, Jimmy O. Yang, Vincent Curatola, Alex Wolff, James Colby, and Themo Melikidze.